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Mauricio Bellini

Publications and source records attributed to Mauricio Bellini.

At least 37 records · Page 2Linked to original sources
arXiv2019

Geometrization of gravito-electromagnetic interactions from boundary conditions in the variational principle

We study the conditions of integrability when the boundary terms are considered in the variation of the geometric contribution of the Einstein-Hilbert action. We explore the emergent physical dynamics that is obtained when we make a displacement from a background Riemann manifold to an extended one, on which the non-metricity is nonzero. Under these circumstances, a classical description of electrodynamics and non-perturbative gravitational waves are considered in the extended manifold, when we variate the action.

gr-qc↗
arXiv2019

Relativistic quantum geometry from a 5D geometrical vacuum: gravitational waves from preinflation

In this work we introduce Relativistic Quantum Geometry (RQG) on a Modern Kaluza-Klein theory by studying the boundary conditions on a extended Einstein-Hilbert action for a 5D vacuum defined on a 5D (background) Riemannian manifold. We introduce a connection which describes a displacement from the background manifold to the extended one, on which the 5D vacuum Einstein equations with cosmological constant included, describes the dynamics of the scalar field $σ$, which is responsible of describing the mentioned displacement and complies with a relativistic quantum algebra that depends on the relativistic observers. In our formalism the extra dimension is considered as space-like, and therefore is a noncompact one. After considering a static foliation on the extra dimension, we obtain the dynamics for the gravitational waves that propagates on a 4D (curved) background, defined on the 4D induced curved Riemannian manifold. Finally, an example, in which we study a pre-inflationary model of the early universe is developed. We obtain some constraints from Planck2018 observations.

gr-qc↗
arXiv2019

The Heisenberg spinor field classification and its interplay with the Lounesto's classification

Dirac linear spinor fields were obtained from non-linear Heisenberg spinors, in the literature. Here we extend that idea by considering not only Dirac spinor fields but spinor fields in any of the Lounesto's classes. When one starts considering all these classes of fields, the question of providing a classification for the Heisenberg spinor naturally arises. In this work the classification of Heisenberg spinor fields is derived and scrutinized, in its interplay with the Lounesto's spinor field classification.

hep-th↗
arXiv2019

Dark energy and large-scales solitonic back-reaction behavior in power-law inflation

We study the behavior of large-scale (cosmological) modes of back-reaction effects during inflation. We find that the group of modes which describes the very large-scale fluctuations of energy density during inflation due to back-reaction effects evolve in phase between them, but there is a tear of these modes with respect to the other modes that describe astrophysical scales. This effect could be the origin for the large-scale homogeneity and isotropy of the universe and could be a manifestation of the existence of dark energy, which is responsible for the accelerated expansion of the universe.

gr-qc↗
arXiv2018

Inflationary expansion of the universe with variable timescale

We explore a cosmological model in which the time scale is variable with the expansion of the universe and the effective spacetime is driven by the inflaton field. An example is considered and their predictions are contrasted between Planck 2018 data. We calculate the spectrum indices and the slow-rolling parameters of the effective potential. The results are in very good agreement with observations.

gr-qc↗
arXiv2018

Gravitons emission during pre-inflation from unified spinor fields

We obtain the equation that describe the conditions of quantization for neutral massless bosons on an arbitrary curved space-time, obtained using a particular theoretical formalism developed in a previous work\cite{MM}. In particular, we study the emission of neutral massless $(1, 2)\hbar$-spin bosons during pre-inflation using the recently introduced unified spinor field theory. We conclude that during pre-inflation (which is governed by an vacuum equation of state), is emitted gravitational radiation, which could be detected in the future, as primordial gravitational radiation.

gr-qc↗
arXiv2018

Inflationary gravitational waves from unified spinor fields

Recent observations of Gravitational Waves (GW) generated by black-hole collisions have opened a new window to explore the universe in diverse scales. Detection of primordial gravitational waves is expected to happen in the next years. However, the standard theory to describe these effects was developed for weak gravitational waves, when their dynamics can be linearized. In this work we develop a non-perturbative formalism to describe GW using the Unified Spinor Fields (USF) theory. The tensor index is calculated and we obtain that it must be $0.0283 <n_T < 0.0407$, in order for the $+$ and $\times$ polarisations modes to have the same spectrum. This imposes some restriction on the constant of self-interaction $3.0018\,<\,ξ^2\,< \,3.0025$ of the fermionic source. The most relevant result here obtained is that the intensity of energy density for GW during inflation is $1.25\times 10^{-4} \left(\frac{m}{H}\right)^2 \, < \,Ω_{GW} \, < \,1.75\times 10^{-4} \left(\frac{m}{H}\right)^2$, where $m$ is the mass of the $1/2$-spin fermionic fields and $H$ the Hubble parameter during inflation. This cut imposes restrictions on the mass of these fields: $\left({m\over H}\right)^2\lesssim 1.1\,h_0^2\times 10^{-11}$.

gr-qc↗
arXiv2018

Collapse driven by a scalar field without final singularity

We explore a collapsing cosmology driven by a scalar field which is minimally coupled to gravity in a spatially at and spherically symmetric, isotropic and homogeneous space-time, with a variable timescale that avoids the final singularity. The equation of state that describes the collapse is $ω=1$. We calculate the back-reaction of the space-time during the collapse and the energy density fluctuations related to this back-reaction has a spectral index $n_s = 0$, favouring short-wavelengths modes to be detected. The interesting is that the amplitude of these fluctuations increase with time when the collapse is sufficiently strong.

gr-qc↗
arXiv2018

Emission of primordial bosonic radiation during inflation

We study the emission of neutral massless $(1, 2)\hbar$-spin bosons during power-law inflation using unified spinor field theory. We shows that during inflation gravitons and photons were emitted with wavelengths (on physical coordinates) that increase as the Hubble radius: $λ_{Ph} \sim a/H$. The quantised action related to these bosons is calculated and results to be a fraction of the Planck constant.

gr-qc↗
arXiv2017

Origin of time before inflation from a topological phase transition

We study the origin of the universe (or pre-inflation) by suggesting that the primordial space-time in the universe suffered a global topological phase transition, from a 4D Euclidean manifold to an asymptotic 4D hyperbolic one. We introduce a complex time, $τ$, such that its real part becomes dominant after started the topological phase transition. Before the big bang, $τ$ is a space-like coordinate, so that can be considered as a reversal variable. After the phase transition is converted in a causal variable. The formalism solves in a natural manner the quantum to classical transition of the geometrical relativistic quantum fluctuations: $σ$, which has a geometric origin.

gr-qc↗
arXiv2017

Pre-inflation: origin of the Universe from a topological phase transition

I study a model which describes the birth of the universe using a global topological phase transition with a complex manifold where the time, $τ$, is considered as a complex variable. Before the big bang $τ$ is a purely imaginary variable so that the space can be considered as Euclidean. The phase transition from a pre-inflation to inflation is examined by studying the dynamical rotation of the time on the complex plane. Back-reaction effects are exactly calculated using Relativistic Quantum Geometry.

gr-qc↗
arXiv2017

Large scale solitonic back-reaction effects in pre-inflation

Using Relativistic Quantum Geometry (RQG), we study the emergence of back-reaction modes with solitonic properties, on astrophysical and cosmological scales, in a model of pre-inflation where the universe emerge from a topological phase transition. We found that, modes of the geometrical field that describes back-reaction effects related to larger scales (cosmological scales), are more coherent than those related to astrophysical scales, so that they can be considered a coarse-grained soliton.

gr-qc↗
arXiv2016

Gravito-magnetic monopoles in traversable wormholes from WIMT

Using Weitzenböck Induced Matter Theory (WIMT), we study Schwarzschild wormholes performing different foliations on an extended (non-vaccuum) 5D manifold. We explore the geodesic equations for observers which are in the interior of a traversable wormhole and how these observers can detect gravito-magnetic monopoles which are dual to gravito-electric sources observed in the outer zone of some Schwarzschild Black-Hole (BH). The densities of these monopoles are calculated and quantized in the Dirac sense. This kind of duality on the extended Einstein-Maxwell equations, relates electric and magnetic charges on causally disconnected space regions.

gr-qc↗
arXiv2016

Geometric back-reaction in pre-inflation from relativistic quantum geometry

The pre-inflationary evolution of the universe describes the beginning of the expansion from a static initial state, such that the Hubble parameter is initially zero, but increases to an asymptotic constant value, in which it could achieve a de Sitter (inflationary) expansion. The expansion is driven by a background phantom field. The back-reaction effects at this moment should describe vacuum geometrical excitations, which are studied with detail in this work using Relativistic Quantum Geometry.

gr-qc↗
arXiv2016

Gravitational waves and magnetic monopoles during inflation with Weitzenböck torsion

We study the variational principle on a Hilbert-Einstein action in an extended geometry with torsion taking into account non-trivial boundary conditions. We obtain an effective energy-momentum tensor that has its source in the torsion, which represents the matter geometrically induced. We explore about the existence of magnetic monopoles and gravitational waves in this torsional geometry. We conclude that the boundary terms can be identified as possible sources for the cosmological constant and torsion as the source of magnetic monopoles. We examine an example in which gravitational waves are produced during a de Sitter inflationary expansion of the universe.

gr-qc↗
arXiv2016

Charged and electromagnetic fields from relativistic quantum geometry

In the Relativistic Quantum Geometry (RQG) formalism recently introduced, was explored the possibility that the variation of the tensor metric can be done in a Weylian integrable manifold using a geometric displacement, from a Riemannian to a Weylian integrable manifold, described by the dynamics of an auxiliary geometrical scalar field $θ$, in order that the Einstein tensor (and the Einstein equations) can be represented on a Weyl-like manifold. In this framework we study jointly the dynamics of electromagnetic fields produced by quantum complex vector fields, which describes charges without charges. We demonstrate that complex fields act as a source of tetra-vector fields which describe an extended Maxwell dynamics.

gr-qc↗